A single-stage three-terminal heterojunction bipolar transistor optoelectronic mixer

A high-conversion gain three-terminal heterojunction bipolar transistor (HBT) optoelectronic mixer has been demonstrated. The maximum obtained intrinsic conversion gain was 10.4 dB. The mixing performance was measured as a function of the dc bias of the device and local oscillator power level. A SPICE-based large signal model was employed to simulate the device. The main nonlinear effects which contributed to the mixing process were the voltage dependence of the dynamic emitter resistance, and the variation of the current gain in the saturation regime.